Parrotfish (family Scaridae) sleeping in a bubble of mucus. It is thought the fish produces this sac to prevent noctural predators such as moray eels from locating it using their acute sense of smell. Parrotfish are found in all tropical seas. Their teeth are fused to form a beak-like structure, which is responsible for their name. They use the beak to bite off pieces of coral from reefs. They then grind up the hard coral in their mouths, digesting the tiny polyps and ejecting the ground coral mineral as white sand. Photographed in Manokwari, West Papua in Indonesia, Asia.